We propose to develop further ultramicro methods (sensitivity 10 to the 12th power mole or less) for the analysis of RNA and RNA derivatives and to apply such methods in detailed studies of the structure (sequences) of RNA, particularly cytoplasmic and mitochondrial transfer RNA, from normal and neoplastic mammalian cells. Methodology is to be designed in such a way that in vivo labeling with radioactive nucleic acid precursors will not be required. Such methods may then be applied to the analysis of RNAs from mammalian tissues, viruses, and of RNA species in general that are difficult to label homogeneously in vivo. The procedures will involve enzymatic and chemical degradation of RNA to oligonucleotides and nucleoside derivatives followed by chemical or enzymatic isotope incorporation into the fragments produced, chromatographic separation, film detection, and quantitative evaluation by scintillation counting. We propose to apply such methods in chemical studies on RNA, particularly tRNA, from various normal and neoplastic tissues. By studying a representative number of tumors we hope to characterize differences between normal and neoplastic RNA in structural terms. Bibliographic references: M. Sivarajan, R.C. Gupta, L.S.Y. Chia, and E. Randerath, Sequence analysis of nonradioactive RNA and DNA fragments by postlabeling, thin-layer chromatography, and in situ exo- or endonuclease digestion, Fed. Proc. 34, 608 (1975), Abstr. 2201. K. Randerath, L.S.Y. Chia, R.C. Gupta, E. Randerath, E.R. Hawkins, C.K. Brum, and S.H. Chang, Structural analysis of RNA by post-labeling: the primary structure of baker's yeast tRNALeuCUA, Biochem. Biophys. Res. Comm. 63, 157-163 (1975).